Yokai Kozo is the benevolent spirit vessel that houses the deceased children who once lived in an orphanage in the mountains. Some time ago, they, along with the nun, and the orphanage itself, burned down in a fire by Sabame after they discovered the landlord made a pact with Maimai-onba to keep the land prosperous by sacrificing people to feed the demoness and her offspring.
Appearance
Yōkai Kozō takes the form of the giant fetus-like monster gathered by the many deceased children spirits. He has an overly-large, bulbous head, with a protruding lump on its forehead. He has big eyes with droopy eyelids and appears to have exotropic strabismus, and has no eyebrows. He has saggy and puffy cheeks, an absent nose, and an odd-shaped mouth resembling puckered lips.
Personality
As seen from Episode 14, he is rather playful, especially around Dororo, as he often harmlessly tackles him to the ground and snuggling him. Before doing so, he stretches his hands out towards Dororo and moves towards him while exclaiming "num-num!". When travelling with Hyakkimaru for a short period of time, he also likes to carry Dororo in his arms. However, Dororo does not like it, as he often screams and struggles in vain while in his arms.
The Yōkai Kozō is also kind and cares for the well-being of others who have given him attention as well as shown him kindness. When Dororo was cornered by Maimai-onba's children in larvae form, he intervened in the nick of time and saved his life. When Dororo asks why, he replies with "Dororo is kind. So I save Dororo."
However, it can be implied that he is fearful of Sabame, for the Yōkai Kozō disappears when he first arrives at the burnt orphanage grounds and greets Hyakkimaru and Dororo.